code: def _option_boolean(arg):
      if not arg or not arg.strip():
          # no argument given, assume used as a flag
          return True
      elif arg.strip().lower() in ("no", "0", "false"):
          return False
      elif arg.strip().lower() in ("yes", "1", "true"):
          return True
      else:
          raise ValueError('"%s" unknown boolean' % arg)
  
imports: import sys, os, glob, shutil, imp, warnings, re, textwrap, traceback
  import sphinx
  import warnings
  from docutils.parsers.rst import directives
  from docutils import nodes
  from docutils import nodes, utils
  import matplotlib
  import matplotlib.pyplot
  import matplotlib.image
  from matplotlib import _pylab_helpers
  import exceptions
label_desc: Use image node_id 3 for calling a global function with example usage: _option_boolean(arg) and returns: True, False, True